In addition, there are also constraints on very light vector boson from the superradiance of spinning black holes [1]}, which potentially exclude two mass windows shown by the yellow shaded bands in Fig. REF . We will not strictly enforce these bounds when we discuss neutrino oscillations at DUNE and Super-K since they depend on models for black hole accretion disks For a brief discussion of this issue see section 10.1.2 of  [2]}..
